Field of the Invention
Generally, the invention pertains to a vertical support. More particularly, the invention pertains to a tripod having support legs which automatically open and close when the tripod is placed on a support surface and lifted from a support surface. This particular improved automatic tripod opens and closes reliably and fluidly with no special care or manipulation needed by the user, which makes it both convenient for consumers to instantly use without needing to fiddle with or adjust the device, and also reliable and therefore appropriate for use with expensive consumer electronics like a smartphone.
Description of Related Art
Tripods are commonly used by professionals in the video and photographic industries to support and stabilize equipment such as cameras, lights, and background screens, and by consumers for a multitude of products. Typically, tripods include at least three pivotally mounted support legs movable between open and closed positions. The support legs stabilize the tripod in a vertical position and prevent movement of the video equipment during filming. The tripods often have telescopic legs or a telescopic center post to allow a user to adjust the height of the equipment being mounted on the tripod. The legs of the tripod pivot to the closed position whereby all three legs extend generally adjacent and parallel to one another.
One problem with this type of prior art tripod is the often awkward process of pivoting the support legs to the open position. Support legs must be moved to the open position, telescopically adjusted to the proper height, and locked in place. Repeated adjustments may be necessary on uneven ground, or if the user is uncertain that the legs are properly adjusted. Simplified tripod bases can be opened more easily but often scrape on the ground or surrounding objects. They also are prone to catch as they fold open, or to open unevenly or in a position that isn't ready to bear weight, especially on uneven ground or in tight quarters.
I have found that adjustment of tripods is a burdensome step in the photography and videography process, especially for amateurs, who aren't as practiced in tripod use as professionals. This lack of familiarity is doubly challenging for amateurs as they also aren't as prepared as professionals for the constant challenge of videography and photography: quickly establishing and then maintaining a readiness to capture the moment, without concern about the readiness of peripheral equipment such as a tripod.
I see that is an increasingly important problem as more and more amateur photographers stop use of single-purpose cameras and video cameras and rely instead on smartphones, which of their nature encourage consumers to expect portability, instant readiness, and ease of use. While consumers in the 1980s, 1990s and early 2000s could commonly be seen in public shooting photo or video using a tripod, today almost no casual videographers such as soccer dads or vacationers can be seen using tripods with smartphone cameras.
Several prior art tripods have been developed which disclose a mechanism to open the support legs of a tripod or similar structure by use of telescoping columns, and by use of moveable legs attached to collars. These date back to 1899, when Leedy filed U.S. Pat. No. 624,662 for “Drum Stand,” which had legs hinged in the middle, with a lower collar sliding on a central shaft. That tripod, like so many patented improved designs to come in the next century, offered users a telescoping pole with nesting columns in order to raise and lower the height of the object being supported. The collars to which the legs were mounted slid and adjusted on the exterior of the outer column. Those hinged legs attached to collars required users to secure them in place before use, and then to manually retract them after use to make the tripod device more compact for transport and storage.
U.S. Pat. No. 624,662 and US Publ. No. 2007/0235605 show either the upper collar, or the lower collar, slideably movable on the central column. The central column is often telescoping. The prior art does not proposes to affix the collars for the hinged legs to each of the telescoping columns, with the result of automatically opening and closing tripod legs that require no manual attention in the course of use. More than a century of tripod innovations has not included such an improvement.
In the last few decades, several patented inventions have sought to create automatically opening and shutting tripods, but they each present drawbacks in ease of use and reliability.
For example, U.S. Pat. No. 4,705,251 discloses a self-erecting tripod apparatus having three outwardly extending legs which are attached to a lower rod which telescopically engages an upper sleeve intermediate the three legs. When the center rod is lowered onto a support surface, the support legs are automatically extended to an outward open position and when the apparatus is lifted from the support surface the support legs will collapse to a closed position under the influence of gravity. A vertically slidable collar extends around the center rod and includes a plurality of links pivotally mounted to the collar and to the support legs. The support legs move between the open and closed positions as the bottom collar moves upwardly and downwardly, respectively, along the center rod.
The design of the '251 tripod automatically opens and retracts, but does so without the benefit of a base that is stable on a variety of surfaces. Its three feet and central pole, rigidly extended, amount to four small points of contact with the support surface. That does not allow for quick, reliable use on uneven surfaces such as hills, and in varied terrain including sand, grass, or foliage. Another problem with the '251 patent's design is that the legs must be angled outward even when the tripod is in the closed position. That makes the tripod unwieldy and able to snag on clothing. It also prevents the tripod from being easily transported in a bag with other items, given that the outwardly angled legs could catch on the bag or other items when the tripod is removed.
A second, more recent example, U.S. Pat. No. 5,934,628 discloses a similar self-erecting tripod apparatus which automatically opens when the tripod is placed on a support surface and automatically closes when the tripod is lifted from the support surface. It has many of the same problems as '251 that would preclude an amateur video user from confidently placing it on a variety of surfaces.
One problem with the '628 design is that the legs extend with the feet in close proximity to the support surface, such as the ground. That means the user must carefully manipulate the tripod so it opens without scraping the ground. The legs extend jerkily and with feet close to the ground due to the design's coupling links, the feet are pivotally attached at one end to a bottom end of the center post and pivotally attached at the other end to the center of the support legs, not the bottom end of the support leg. It is unsuitable for uneven surfaces such as grass or turf due to the angle at which the legs extend, offering little clearance from the ground.
Therefore, the need exists for a tripod having support legs which automatically open and close when the tripod is placed on a support surface and when removed from the support surface, respectively, which allows the support legs to close to a vertical position parallel and adjacent to the center post when in the closed position, and which does so with legs opening upwards and downwards, firmly landing on a variety of support surfaces.